This invention relates to compositions and methods useful in contact lenses. More particularly, the invention relates to compositions and methods in which contact lenses are stored. The present invention provides compositions containing polyanionic components.
The current commercial process for packaging contact lenses is to place a single contact lens in a glass vial, fill the vial with saline solution, cap and seal the vial and then heat sterilize of the lens. This process is also used for daily-disposable lenses. Indeed, this packaging process results in one of the meritorious attributes with the use of daily-disposable lenses: comfort associated with wearing fresh lenses every day. However, symptoms of discomfort, fatigue, and irritation at the end of the day are common among daily-disposable lens wearers. To alleviate or reduce the aforementioned symptoms, incorporation of a comfort enhancing agent(s) and/or a lubricant(s) into the lens storage medium is highly desirable, which also can make the extension of the lens wearing time possible. This is critical to the consumer of a daily-disposable lens.
Since the current packaging process requires heat sterilization, commonly used lubricants like polyvinyl alcohol (PVA), polyethylene glycol (PEG), hydroxypropyl methylcellulose (HPMC) are not suitable for this purpose due to their physio-chemical instabilities. A suitable lubricant should have a high affinity toward water and contact lens surface so that a hydration layer can be formed on the lens surface. For example, upon heating, HPMC in aqueous solution loses water from the hydration. As a result, it loses lubricity on the lens surface.
Bhagat, U.S. Pat. No. 5,460,834 discloses the use of cellulose polymers for use in physiological tear compositions. However, this patent does not disclose use of such cellulose polymers for providing a lubricant in conjunction with a contact lens storage medium.
It would be advantageous to provide a new contact lens storage system for daily-disposable contact lenses.